Summary: A new study reports younger pregnant and postpartum women could be at a higher risk of stroke than older pregnant women and non-pregnant women of the same age.
Source: JAMA.
Younger pregnant women, including the postpartum period up to six weeks after delivery, appeared to be at increased risk of stroke compared with their nonpregnant counterparts, and that increased stroke risk was not associated with older pregnant women, according to a new article published online by JAMA Neurology.
Eliza C. Miller, M.D., of Columbia University, New York, and coauthors used data on all stroke admissions in the state of New York from 2003 to 2012 to determine age-specific incidence risk ratios for pregnancy-associated stroke (PAS) compared with nonpregnancy-associated stroke (NPAS).
There were 19,146 women hospitalized with stroke during the study period and 797 (4.2 percent) of the women were pregnant or postpartum.
The authors report the incidence of PAS in women 12 to 24 years old was 14 events per 100,000 pregnant/postpartum women compared with a NPAS incidence of 6.4 per 100,000 nonpregnant women. In women 25 to 34, the PAS incidence was 21.2 per 100,000 pregnant women and NPAS incidence was 13.5 per 100,000 nonpregnant women.
In older women 35 to 44, PAS incidence was 33 per 100,000 pregnant women and NPAS incidence was 31 per 100,000 nonpregnant women. In women 45 to 55, PAS incidence was 46.9 per 100,000 pregnant women compared with NPAS incidence of 73.7 per 100,000 nonpregnant women.
Although older pregnant women had higher rates of stroke in pregnancy than younger pregnant women, their risk of stroke was similar to women of their own age who were not pregnant. But in women under 35, pregnancy increased the risk of stroke, more than doubling it in the youngest group, the authors report.
PAS accounted for 15 percent of strokes in women 12 to 24; 20 percent of strokes in women 25 to 34; 5 percent of strokes in women 35 to 44; and 0.05 percent of strokes in women 45 to 55, according to the results.
Women with PAS were less likely than women with NPAS to have vascular risk factors, diabetes and active smoking. Death was also lower among women with PAS compared with NPAS. The authors note different underlying stroke mechanisms may factor into why younger women had higher stroke risk during pregnancy.
Study limitations include billing data that lack specificity, especially in regard to PAS.
“In our sample of all women aged 12 to 55 years hospitalized with stroke in New York State from 2003 to 2012, younger pregnant and postpartum women – but not older women – were at increased risk of stroke compared with their nonpregnant contemporaries. These results have potential implications for research aimed at better characterizing and preventing PAS and clinically in terms of counseling patients. Although older women have an increased risk of many pregnancy complications, a higher risk of stroke may not be one of them. Our results should be interpreted with caution and regarded primarily as hypothesis generating; more research is needed to investigate why younger women may have an increased risk of PAS,” the study concludes.
Source: Karin Eskenazi – JAMA
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Original Research: Full open access research for “Risk of Pregnancy-Associated Stroke Across Age Groups in New York State” by Eliza C. Miller, MD; Hajere J. Gatollari, MPH; Gloria Too, MD; Amelia K. Boehme, PhD, MSPH; Lisa Leffert, MD; Mitchell S. V. Elkind, MD, MS; and Joshua Z. Willey, MD, MS in JAMA Neurology. Published online October 24 2016 doi:10.1001/jamaneurol.2016.3774
[cbtabs][cbtab title=”MLA”]JAMA “Increased Stroke Risk For Younger Pregnant Women.” NeuroscienceNews. NeuroscienceNews, 23 October 2016.
<https://neurosciencenews.com/pregnancy-stroke-risk-5334/>.[/cbtab][cbtab title=”APA”]JAMA (2016, October 23). Increased Stroke Risk For Younger Pregnant Women. NeuroscienceNew. Retrieved October 23, 2016 from https://neurosciencenews.com/pregnancy-stroke-risk-5334/[/cbtab][cbtab title=”Chicago”]JAMA “Increased Stroke Risk For Younger Pregnant Women.” https://neurosciencenews.com/pregnancy-stroke-risk-5334/ (accessed October 23, 2016).[/cbtab][/cbtabs]
Abstract
Risk of Pregnancy-Associated Stroke Across Age Groups in New York State
Importance Older age is associated with increased risk of pregnancy-associated stroke (PAS). Data are limited on age-specific incidence ratios of PAS compared with stroke risk in nonpregnant women.
Objectives To assess the risk of stroke by age group in pregnant and postpartum women compared with their nonpregnant contemporaries and to compare risk factors across age groups in the exposed (pregnant/postpartum) and unexposed (nonpregnant) populations.
Design, Setting, and Participants International Classification of Diseases, Ninth Revision, billing codes from the calendar year 2003-2012 New York State Department of Health inpatient database and population data were used to identify all women aged 12 to 55 years with cerebrovascular events, including transient ischemic attack, ischemic and hemorrhagic stroke, cerebral venous thrombosis, and nonspecified PAS. The cumulative incidence of PAS per 100 000 pregnant/postpartum women vs nonpregnancy-associated stroke (NPAS) per 100 000 women in age cohorts of 24 years or younger, 25 to 34, 35 to 44, and 45 years or older was calculated. Risk factors between groups were compared using logistic regression models. The study included data from calendar years 2003 through 2012. Data analysis was performed from July 11, 2015, to July 16, 2016.
Exposures Pregnancy, including the postpartum period up to 6 weeks after delivery.
Main Outcomes and Measures Incidence risk ratios (IRRs) for stroke per age cohort, defined as cumulative risk of stroke in the exposed population divided by cumulative risk of stroke in the unexposed population, were determined, and stroke risk factors and mortality were compared between populations.
Results There were 19 146 women hospitalized with stroke during the study period; 797 of the women were pregnant/post partum. The overall median (interquartile range) age of the women was 31 (25-35) years in those with PAS and 48 (41-52) years in those with NPAS. The incidence of PAS in women aged 12 to 24 years was 14 events per 100 000 pregnant/postpartum women vs NPAS incidence of 6.4 per 100 000 nonpregnant women (IRR, 2.2; 95% CI, 1.9-2.6); for ages 25 to 34 years, 21.2 per 100 000 vs 13.5 per 100 000 (IRR, 1.6; 95% CI, 1.4-1.7); for ages 35 to 44 years, 33 per 100 000 vs 31 per 100 000 (IRR, 1.1; 95% CI, 0.9-1.2); and for ages 45 to 55 years, 46.9 per 100 000 vs 73.7 per 100 000 (IRR, 0.6; 95% CI, 0.3-1.4). PAS accounted for 18% of strokes in women younger than 35 years vs 1.4% of strokes in women aged 35 to 55 years. Women in the NPAS group vs the PAS group had more vascular risk factors, including chronic hypertension (age <35 years: 437 [15.7%] vs 60 [9.8%], P < .001; age 35-55 years: 7573 [48.6%] vs 36 [19.3%], P < .001), diabetes (age <35 years: 103 [3.7%] vs 9 [1.5%], P = .002; age 35-55 years: 2618 [16.8%] vs 12 [6.4%], P < .001), and active smoking (age <35 years: 315 [11.3%] vs 29 [4.8%], P < .001; age 35-55 years: 2789 [17.9%] vs 10 [5.3%], P < .001); and had higher mortality (age <35 years: 288 [11.3%] vs 37 [6.5%], P < .001; age 35-55 years: 2121 [13.4%] vs 14 [6.1%], P < .001).
Conclusions and Relevance Younger women, but not older women, have an increased stroke risk during pregnancy and post partum compared with their nonpregnant contemporaries. These results suggest that pregnancy does not increase the risk of stroke in older women.
“Risk of Pregnancy-Associated Stroke Across Age Groups in New York State” by Eliza C. Miller, MD; Hajere J. Gatollari, MPH; Gloria Too, MD; Amelia K. Boehme, PhD, MSPH; Lisa Leffert, MD; Mitchell S. V. Elkind, MD, MS; and Joshua Z. Willey, MD, MS in JAMA Neurology. Published online October 24 2016 doi:10.1001/jamaneurol.2016.3774
